Helicopter speed control system



Jan. 15, 1963 c. w. CHILLSON -ETAL 3,073,328

HELICOPTER SPEED CONTROL SYSTEM Original Filed April 10, 1956 3Sheets-Sheet 1 EH Z E DVVARD K. HINE m5 ATTDFQNEY Jan. 15, 1963 c. w.CHILLSON'ETAL ,07

HELICOPTER SPEED CONTROL SYSTEM Original Filed April 10, 1956 I 3Sheets-Sheet 2 E5 EDW HIS ATTURNEY QNx aiaai g TE WWIllllIllllllllllllllllllllllllilllllll Jan. 15, 1963 c. w. CHILLSON ETALI 3,073,323

HELICOPTER SPEED CONTROL SYSTEM Original Filed April 10, 1956 5Sheets-Sheet 3 ARLEE vJ c fifiii m EDWARD KHINE H15 ATTEIRNEY UnitedStates Patent Ofitice 3,073,328 Patented Jan. 15, 1963 3,073,328HELICOPTER SPEED CONTROL SYSTEM Charles W. Chillson, Packanack Lake, andEdward K.

Hine, North Caldwell, N.J., assignors to Curtlss- Wright Corporation, acorporation of Delaware Original application Apr. 10, 1956, Ser. No.577,229, pow Patent No. 2,957,687, dated Oct. 25, 1960. Divlded and thisapplication Jan. 2, 1959, Ser. No. 784,677 Claims. (Cl. 137-18) Thisinvention relates to speed control arrangements for rotary wing systems,as on helicopters, and more particularly includes a rotor speedresponsive governor, acting on the rotor prime mover, along with manualcontrol and adjusting instrumentalities. The invention is a division ofPatent Application Serial No. 577,229, filed April 10, 1956, now PatentNo. 2,957,687 issued October 25, 1960.

A conventional helicopter rotor control system includes a member toadjust collective pitch of the rotor blades, along with a grip on themember movable to adjust the throttle. Collective pitch adjustment is aprimary control for the air vehicle to regulate its lift; adjustment ofthe engine throttle is a concurrent primary control to maintain rotorspeed at a desired level during changes in load on the rotor resultingfrom lift changes. It is desirable, to simplify the pilots activities,to enable rotor speed to be governed at times, avoiding the need forconcurrent manual collective pitch and throttle adjustment. Yet changesin the rotor speed must always be within the pilots immediate command toenable him to change governor setting or to enable manual throttlecontrol.

Other desirable features in a rotor speed governor system includearrangements to prevent rotor overspeed, to provide accurate and fastthrottle response by incorporating derivative stabilization in thegovernor action, to provide for governor speed adjustment concurrentlywith, and following rotor speed adjustment when the governor isdisconnected from throttle control, to provide throttle grip follow-upof governor action when the rotor is under governor control; to providefor closed engine throttle for shut down when the control is connectedto the governor, and to provide means for the governor to actautomatically as a speed limiter when the system is set for manualcontrol.

Objects of the invention are to provide a governor control system tomeet the foregoing, and other, desirable features, and to provide acompact, all-mechanical appa-; ratus which is positive and independentof secondary power supplies or sources. Other objects of the inventionwill appear as a more detailed description of the invention porceeds.

Principal features of the invention are shown in the annexed drawings,in which similar reference characters designate similar parts, and inwhich:

FIG. 1 is a generalized side elevation of a helicopter showing the usualarrangement of certain principal components, along with a practicablelocation for a rotor governor,

FIG. 2 is a schematic diagram of one command arrangement for ahelicopter governor and throttle,

FIG. 3 is a schematic longitudinal section of a gover nor,

FIGS. 4 and 5 are schematic diagrams of alternative helicopter governorand throttle command arrangements.

For general orientation, reference may be made to FIG. 1 wherein ahelicopter fuselage is indicated by the outline 6. A vertical shaft 7 isdriven by a prime mover or engine 8 of any desired type, the shaftdriving the rotor or rotary wing system 9. A power take-ofi 10 may drivea shaft 11 leading to a tail rotor, used for directional control as iswell known. A prime mover or engine speed and power controller isindicated at 12, wihch may comprise part of the fuel control system tothe prime mover.

The rotor 9, while having other controls, not shown, such as cyclicpitch con-trol, includes a collective pitch adjuster known in the artand indicated bythe rectangle 13. Collective pitch is adjusted by acontrol rod 14, linked to a control assembly '15, and operated by apilotmanipulated collective pitch lever 16. The lever carries arotatable throttle grip 17, drivably connected through suitablemechanism, not shown, to a control rod 18 connected to the controller orthrottle 12. This rod is also connected to actuate, or be actuated by,an output. arm 19 of a governor assembly 20. The description will now bedirected to parts of the governor.

The governor includes input shaft 22 driven by the prime mover at fixedspeed ratio. This drives an integral speed changer 26 and a proportionalspeed changer 24 and a ball speeder section 28 through a plate 30 and adrive cage 32. Action of the governor rotates an output gear 34 througha ball differential 36 comprising two driven rings 38 and 40, a reactionring 42, and a ball cage 44, the latter being secure on the gear 34. Theoutput gear 34 drives a pinion 46 secured on a shaft 47 which isangularly rockable through a small angle in a bearing 48. This shaftcarries two worms 50 and 52, the former being engageable with a wheel53, and the latter with a wheel 54. By shifting the shaft 47 by anover-center toggle mechanism 56, operated by a manual control 58, worm50 is engaged with wheel 53, or worm 51 is engaged with wheel 54. Theformer is the automatic, or governor control connection wherein thegovernor output shaft 47 drives the throttle of the engine through rod18 to maintain the engine speed to that for which the governor is set.The latter is the manual control connection wherein the throttle rod isactuated manually while the governor speed setting may follow the actualspeed of the engine. The wheel 54 adjusts the governor speeder settingand, as will be seen, an additional manual setter may be used inconjunction with, or may supplant, the setting wheel 54.

Now reference may be had to FIG. 2 which shows a presently preferredcommand arrangement for the governor. The governor 20 is driven bypowerplant 8 through a mechanical drive connection 62; the twist grip 17of the lever 16 is connected by gearing 64 through the rod 18 to thegovernor output lever 19 and the engine throttle 12. The governor isprovided with a solenoid 66 acting on an armature 67 linked to thegovernor manual-automatic selector 58. A circuit for solenoid 66includes a power source 68, a master switch 69, and a button switch 70mounted atop the throttle grip 17. This button switch may be one whichis normally up to close the circuit of solenoid 66, and which is pushedto open the circuit. The circuit is arranged preferably for closure tomove lever 58 to the automatic setting, and for opening to move lever 58to manual. This renders the arrangement fail-safe in case of electricalfailure as will be described. A button latch or hold-down may beprovided to retain the system in manual control condition.

When the circuit is closed, the governor is connected to operate theengine throttle; the grip 17 follows governor energized throttleadjustment whereby the pilot may at all times sense throttle action.When the circuit is open, governor control of the throttle isdisconnected and the throttle is manipulated directly by the grip 17.During manual throttle operation, the governor lever 19 is moved toreset the governor speed setting to the engine speed resulting from thethen current throttle setting. Thus, when shifting between manual andautomatic, there is no sudden call for a drastic speed change. For

instance, suppose the system is on automatic and a change is desiredfrom speed A to speed B. The pilot shifts from automatic on speed A tomanual and adjusts the throttle grip 17 to attain speed B. During themanual speed transition, the governor desired speed setting follows theactual speed so that when the shift is again made from manual toautomatic, the new automatic operation will be at speed B.

In the governor, an element 72 (FIG. 2) is provided which moves inaccord with instant engine speed. This, when some desired maximum speedmay be reached, closes a switch 73 in parallel with switch 70, shiftingthe governor to automatic operation if it had been on manual. Thegovernor takes command of the throttle to prevent further speedincrease, thus acting at a speed limiter. Should it be necessary for thepilot to retain manual command of the system, regardless of overspeed,he can open the master switch 69, which prevents shift of the governorto, or retention in, the automatic position.

FIG. 4 shows at alternative command arrangement wherein the governor isprovided with an independent governor speed setting control 54acorresponding to the worm wheel 54 in FIG. 3 by which governor speedsetting is adjusted. In FIG. 4, the collective pitch control lever 16 isprovided with a rotatable and slidable throttle grip 17a slidable on androtatable with and with respect to the tubular, rotatable lever 16. Thelever 16, as previously covered, is swingable about a pivot and controlscollective pitch. It is also rotatable about its own axis, carrying abevel pinion 76 engaged with a bevel gear 77, the latter operating thethrottle control rod 18. Axial movement of the grip 17a on the lever 16operates a push-pull assembly 79 of any suitable type, which connects tothe manual-automatic shift lever 58 on the governor 20. The arrangementis such that downward movement of the grip 17a shifts lever 58 to manualand upward movement to automatic. The grip is shown in its normal upwardposition whereat it is held by a detent 80 on the lever 16', engaging anopening 82 in the grip. In its downward position the grip 17a is held bya detent 84 which engages the grip opening 82. The grip 17a is providedwith teeth 86 at its upper end, and is movable upwardly against a spring88, beyond the said normal upward position. When so moved, teeth 86engage teeth 90 of a rotatable cap 91 secured to a rod 92 passingthrough the lever 16, to bevel pinion 94 adjacent the lever swing pivot.Pinion 94 engages a bevel gear 95, coaxial with gear 97, which has alever 96 connected to a push-pull connection 98, connected to andactuating the governor speed setting lever 54a.

Grip 17a is keyed to lever 16 at 100 and rotates with it at all timesexcept when the grip is raised against spring 88 to adjust governorsetting. When so raised, the grip disengages the key 100, but re-engagesit as soon as the governor setting adjustment is complete. Under bothmanual and automatic operating conditions the grip rotates withlever 16;in automatic, the grip follows the governor, while in manual, the gripcontrols throttle setting. The arrangement described provides a completeone-hand control for collective pitch, throttle actuation, governorselection and governor setting.

In an arrangement of this sort, the worm connection 51--54 of FIG. 3 isomitted since the governor setting is controlled separately by the lever54a, instead of by coupling at times to the governor output.

FIG. 5 shows another command system which is, in eifect, anall-mechanical arrangement functionally like the command arrangement ofFIG. 2. Herein, the grip 17 rotates the gears 76 and 77 and eitherdrives (in manual control) or is driven by (in automatic control) thecontrol rod 18 leading to the governor and engine throttle. As in FIG.4, sliding of the grip in or out along the collective pitch lever movesthe governor selector to manna or automatic respectively through aconnection such as the push-pull cable 79. When the grip 17 is in themanual position, governor setting follows the speed of the enginethrough the governor mechanism shown in FIG. 3, as well as the grip 17controlling the engine throttle directly through the connection 18. Whenthe grip 17 is shifted to automatic, the governor controls the enginethrottle, to hold the speed at which the engine was operating at thetime the shift from manual to automatic was made. When operating onautomatic, governor action is transmitted to the grip 17 for feel by thepilot.

There are many possible variations and modifications for the commandsystem, and the three shown in FIGS. 2, 4 and 5 are chosen asnon-limiting, practical and desirable examples.

Reference should be had again to FIG. 3. The description of the governorshown therein, already given, was incomplete inasmuch as it referredonly to components having a direct connection with the control andcommand system. Following is a more detailed description which willpromote a more complete understanding of governor construction andoperation. The speeder section 28 of the governor comprises anon-rotating conical race 110, and an opposed, axially movablenon-rotating conical race 1 12, forming part of the member 72. Betweenthese races a plurality of balls 115 are disposed, these being spacedcircumferentially by a driving retainer 114 connected with the drivingsleeve 32 and driven by the input shaft 22 through the drive plate 30.As the balls are spun about the governor axis by rotation of shaft 22,they exert centrifugal force against the races and 112, tending tospread them apart; specifically, tending to move the race 112rightwardly as shown. This movement is resisted by the speeder springs116 and 118, which are held at their right ends by a fixed cup 120, andwhich bear at their left ends on a cup 122 integral with the member 72carrying the race '112. The balls rotate against the races 110 and 112and assume a circular orbit whose radius is a function of the rotationalspeed of the shaft 22. Also, the race 112 and cup 122 assume an axialposition which is a function of rotational speed. Thus, for any specificspeed of the speeder system there is a corresponding axial position ofthe cup 122.

When a certain set speed is desired, the position of the cup 122 isestablished relative to a speeder output member 124 with the latter in aneutral position. This position is attained through a differential lever126, the upper end of which is engaged under normal conditions by a pin128 on the member 72. The lower end of the lever normally engages a pin130 on the output member 124, and the lever is pivoted intermediate itslength, at 132, on a speed setting member 134.

The latter is axially adjustable by a speed setting cam 136, adjusted bythe speed setting wheel 54, through a lever 138, a link and a lever 142.This is pivoted to a bushing 144 and engages a pushrod 146 in turnengaging the speed setting member 134. The cam 136 and associatedelements are held from free rotation when the worm 51 and wheel 54 aredisengagegd by a light drag brake, not shown.

The speeder section output member 124 is secured for axial movement withand for rotation relative to an adjuster 148 through a thrust bearing150, the adjuster 148 being urged rightwardly by a spring 152. By thisspring, the adjuster pin 130 is held against the lever 126, and thelever is held against the pin 128 so that the adjuster is caused tofollow axial excursions of the cup 122 for any fixed setting of thepivot 132.

The adjuster 148 which comprises the shifter for the integral ball speedchanger 26 acts through leaf spring 200 connecting these parts. Thespeed changer is driven by the sleeve 32 and operative to rotate itsoutput race in one direction or the other relative to a fixed race 156according to the tilt of the ball unit 158. This ball speed changer isof the type shown and claimed in Patent No.

2,860,530 of Edward K. Hine and Charles W. Chillson issued November 18,1958. The speed changer output race 1-54 moves according to theintegrated speed error of the governor shaft 22 relative to the setspeed datum established by the position of the speed setting member 134.The output race 154 of speed changer 26 is integral with two otherraces; namely, an input race 160 to the second speed changer .24, andthe input race 38 to the output differential 36 of the governorassembly.

The second speed changer 24, similar in general to 26, includes anoutput race 162, ball assemblies 164, a ratio adjuster 166 and leafspring 200 connecting adjuster 166 with assemblies 164. The output race162 is integral with the input race 40 of ball dilferential 36, and alsois integral with a nut 168. This nut engages a nonrotating axiallyshiftable screw 170, held from rotation by a tang 172 engaging thegovernor housing.

The screw 170 carries a thrust bearing 174 engaging a shaft 176 whichjoins the drive dog 22 to the plate 30 and ratio adjuster 166, theserotating elements being axially shiftable with the nut 168 through thebearing 174. Axial shifting of the adjuster 166 regulates the driveratio of the speed changer 24 in transmitting movement from race 160 andrace 162. The speed changer 24 operates to mathematically differentiate,or calculate the first derivative of the integrated speed errorrepresented by rotation of the race 154. Thus, the position of the races162 and 40 is proportional to the speed error. The screw connection168170 operates to adjust the ratio of the speed changer 24, and torestore the changer to 1:1 ratio upon eradication of speed error.

The differential 36 sums the integral and proportional speed erroroutputs of the two speed changers and its output gear 34 moves accordingto the summed quantities. Thus, the position and movement of the gear 34represents a derivative stabilized signal, applied to the gear 46 andrelated mechanism. This gear 46 calls for (1) throttle adjustment torestore engine speed to normal if the selctor 58 is set for automaticcontrol or (2) governor speed setting adjustment to correspond to theexisting speed of governor input 22 if the selector 58 is set for manualcontrol.

In addition to the governor structure described, several additionalfeatures are incorporated.

The spring 152, acting between speed changer adjusters 148 and 166,tends to urge both of them toward ratio positions which are opposite tothose which are urged by operation of controlling instrumentalities.

The required frictional engagement of the speed changer races and theirballs, and of the components of the ball differential 36, is all securedthrough the force exerted by a single loading Spring 178 acting betweenthe governor housing and the sloped-face reaction race 42 of thedifferential 36. t I

The governor incorporates additional automatic contro provisions, toprovide overspeed protection to close the throttle of the engine at apre-selected low speed when the engine is shut down, and to providecompensations in the speed setting of the governor due to loadconditions. These will be described in the order above set forth.

As formerly described briefly, should the engine and governor tend toincrease in speed when the command system is set for manual control (seeFIG. 3), the speeder section member 72 will move to the right. Theposition of this member, as implied before, is a direct function ofspeed. In FIG. 2, the element 72 which corresponds to the member 72 ofFIG. 3, is operative, at a certain speed, to close the switch 73energizing the solenoid 66 and placing the system on automatic controlinstead of manual control.

Thereupon, depending on the adjustment of switch 73 as to the speed ofthe governor at which it closes, the governor will control the enginethrottle to prevent further speed increase. Should the pilotdeliberately choose an over-speed operating condition, he may open themaster switch 69 to prevent automatic system operation.

In a helicopter or other governed system, it is generally desirable toclose the engine throttle when the engine is shut down to enablerestarting of the engine with closed or substantially closed throttle.In effect, this imposes a need for automatic throttle closing when theengine speed drops below a certain level, say of normal engine idlingspeed. Shutting off of the engine is normally accomplished by leaningthe fuel-air mixture to the engine or by cutting ignition or both.

In the governor described herein, a decrease in speed normally resultsin moving member 72 to the left which creates a call for open throttle,to provide more power to bring the speed up to the set value. Uponengine shut down, this is opposite to the effect desired. To close thethrottle on shut down, when the member 72 moves leftwardly in responseto low speed, the portion 122 of this member moves leftwardly andengages an abutment 182 secured on the stem 134, forcing the pivot 132leftwardly. The lever is thus moved bodily to the left, stroking thespeed changer adjuster 124 leftwardly and operating the speed changersto drive the output gears 34 and 46 to a throttle closing position,through elements 47, 53, 19 and 18.

When a throttle load change occurs, the load change is reflected intothe speed changers and creep may occur therein which, if notcompensated, introduces throttle setting errors. Means are provided,proportional to the torque load on the speed changers, to compensatethis creep which has the effect of removing regulation errors due tospeed changer operation. Mechanism for this purpose includes anoscillatory mounting 184 for the non-rotating speed changer race 156 andits carrier 186, the race and carrier being urged to a certain positionby tangentially acting springs 188. The carrier 186 includes a slopedcam 190 which is engaged by a push rod 192 in contact with the link 142of the adjusting mechanism. Upon torque reaction displacement of thecarrier 186, the elements 192 and 142 adjust the ratio adjuster 124, 148an incremental amount to compensate speed changer creep, at least inpart.

The governor shown herein is isochronous, which under most conditions isa most desirable characteristic, since a desired speed is maintainedregardless of throttle setting or driven load. Under some conditions ofoperation, droop in the system is desirable and means are provided toincorporate droop to any degree desired. To this end, the wheel 53,whose rotational position is directly related to throttle positionthrough the connections 18 and 19, is drivably connected at 196 to a cam198 engaging the link 138 of the speeder adjusting mechanism. The cam isformed to increase or decrease the governor speed setting according tothrottle position, to

- insert droop to any desired degree.

In a system wherein two governed prime movers are driving a single load,a small amount of droop is needed in the governors so that the two primemovers can each drive their share of the load at desired speed. The cam198 might be shaped to provide for this.

In a helicopter, a different governor sensitivity is required in the lowengine power range when the engine is decoupled from the rotor, from thehigher power range when the engine and rotor are coupled. The cam 198furnishes a means for providing an effective difference in governorsensitivity between the high power and the low power range. At throttlesettings corresponding to the rotor driving range, the cam 198 may beshaped to yield no speed setting change or droop.

The governor just described is to be taken as but one example of variousgovernor arrangements which might be used in control systems embodyingconcepts of the invention. Any other governors with generally similarfunctional attributes may be used,

Also, it should be understood that while several command systemsembodying the features of the invention have been presented, other formsof the invention are also possible. Various changes and modificationsmay be made in the particular forms of the invention shown and describedwithout departing from the spirit and scope of the invention as definedin the appended claims.

We claim:

1. In combination, governor mechanism for controlling the speed of aprime mover, the governor mechanism including means for adjusting thespeed setting therof, a mechanical linkage means which includes anoutput shaft and an input shaft rotatable by the governor mechanism,said input shaft being adapted to operate said output shaft, a controlelement connected to said linkage means and adapted to manually operatesaid output shaft, selector means operated in conjunction wtih saidcontrol element to switch the operation of said output shaft from saidinput shaft to said control element and vice versa, and means forconnecting said input shaft to said speed setting means when the outputshaft is disconnected from the input shaft.

2. In combination, a prime mover, governor mechanism driven thereby forcontrolling prime mover speed, the governor mechanism including anelement movable according to prime mover speed, a mechanical linkagemeans which includes an output shaft connected with the prime mover andan input shaft rotatable by the governor mechanism, said input shaftbeing adapted to operate said output shaft, a control element connectedto said linkage means and adapted to manually operate said output shaft,selector means operated in conjunction with said control element toswitch the operation of said output shaft from said input shaft to saidcontrol element and vice versa, and means responsive to certainpositioning of the first mentioned element resulting from overspeed ofthe prime mover to connect the input shaft to the output shaft shouldthe output shaft then be under manual control.

3. A control system comprising a mechanical linkage means which includesan output shaft and a rotatable input shaft, said input shaft beingadapted to operate said output shaft, a control element connected tosaid linkage means and adapted to manually operate said output shaft,and selector means operated in conjunction with said control element toswitch the operation of said output shaft from said input shaft to saidcontrol element and vice versa, said control element including a twistgrip movable about its own axis for operating said output shaft andmovable axially for actuating said selector means.

4. A control system comprising a mechanical linkage means which includesan output shaft and a rotatable input shaft, said input shaft beingadapted to operate said output shaft, a control element connected tosaid linkage means and adapted to manually operate said output shaft,and selector means operated in conjunction with said control element toswitch the operation of said output shaft from said input shaft to saidcontrol element and vice versa, said control element including a twistgrip movable about its own axis for operating said output shaft and aswitch on the twist grip for actuating said selector means.

5. In combination, a prime mover, governor mechanism driven thereby forcontrolling prime mover speed, the governor mechanism including meansfor adjusting the speed setting thereof, a mechanical linkage meanswhich includes an output shaft connected with the prime mover and aninput shaft rotated by the governor mechanism, said input shaft beingadapted to operate said output shaft, a rotatable and axially shiftablecontrol element connected to said linkage means, and selector meansresponsive to axial shift of the control element to switch the operationof said output shaft from said input shaft to said control element andvice versa, mechanism responsive to rotation of the control element inone axial position for actuating said output shaft, and mechanismresponsive to rotation of the control element in another axial positionfor actuating the means for adjusting the speed setting of the governormechanism.

References Cited in the file of this patent UNITED STATES PATENTS2,491,372 Gille Dec. 13, 1949, 2,619,342 Sparrow Nov. 25, 1952 2,613,751Donovan et al Oct. 14, 1952 2,640,551 Plumb June 2, 1953 2,664,958Dancik Jan. 5, 1954 2,679,296 Morain May 25, 1954 2,742,792 Lacoste Apr.24, 1956 2,941,601 Best June 21, 1960

1. IN COMBINATION, GOVERNOR MECHANISM FOR CONTROLLING THE SPEED OF A PRIME MOVER, THE GOVERNOR MECHANISM INCLUDING MEANS FOR ADJUSTING THE SPEED SETTING THEREOF, A MECHANICAL LINKAGE MEANS WHICH INCLUDES AN OUTPUT SHAFT AND AN INPUT SHAFT ROTATABLE BY THE GOVERNOR MECHANISM, SAID INPUT SHAFT BEING ADAPTED TO OPERATE SAID OUTPUT SHAFT, A CONTROL ELEMENT CONNECTED TO SAID LINKAGE MEANS AND ADAPTED TO MANUALLY OPERATE SAID OUTPUT SHAFT, SELECTOR MEANS OPERATED IN CONJUNCTION WITH SAID CONTROL ELEMENT TO SWITCH THE OPERATION OF SAID OUTPUT SHAFT FROM SAID INPUT SHAFT TO SAID CONTROL ELEMENT AND VICE VERSA, AND MEANS FOR CONNECTING SAID INPUT SHAFT TO SAID SPEED 